The processes involved in tumor growth, progression, and metastasis are mediated by signaling pathways that are activated in cancer cells. The ERK pathway plays a central role in regulating mammalian cell growth by relaying extracellular signals from ligand-bound cell surface receptor tyrosine kinase (RTK's) such as erbB family, PDGF, FGF, and VEGF receptor tyrosine kinase. Activation of an RTK induces a cascade of phosphorylation events that begins with activation of Ras. Activation of Ras leads to the recruitment and activation of Raf, a serine-threonine kinase.
Activated Raf then phosphorylates and activates MEK1/2, which then phosphorylates and activates ERK1/2. When activated, ERK1/2 phosphorylates several downstream targets involved in a multitude of cellular events including cytoskeletal changes and transcriptional activation. The ERK/MAPK pathway is one of the most important for cell proliferation, and it is believed that the ERK/MAPK pathway is frequently activated in many tumors. Ras genes, which are upstream of ERK1/2, are mutated in several cancers including colorectal, melanoma, breast and pancreatic tumors. The high Ras activity is accompanied by elevated ERK activity in many human tumors. In addition, mutations of BRAF, a serine-threonine kinase of the Raf family, are associated with increased kinase activity. Mutations in BRAF have been identified in melanomas (60%), thyroid cancers (greater than 40%) and colorectal cancers. These observations indicate that the ERK1/2 signaling pathway is an attractive pathway for anticancer therapies in a broad spectrum of human tumors. (M. Hohno and J. Pouyssegur, Prog. in Cell Cycle Res. 2003 5:219)
Therefore, small-molecular inhibitors of ERK activity (i.e., ERK1 and ERK2 activity) would be useful for treating a broad spectrum of cancers, such as, for example, melanoma, pancreatic cancer, thyroid cancer, colorectal cancer, lung cancer, breast cancer, and ovarian cancer. Such a contribution is provided by this invention.
There is a continuing need for new and novel therapeutic agents which can be used for cancer and hyperproliferative conditions. The Raf/MEK/ERK pathway is an important signaling pathway which is frequently over-expressed and/or overactive in many cancerous tissues. Design and development of new pharmaceutical compounds is essential.